As is well known in the packaging field, generally a product is manufactured by forming a container wall in a desired shape (such as round, oval, rectangular and the like), attaching a base to the container and filling the container with the goods to be packaged. Once filled, the fitment and lid are secured to the open end of the container. The container fitment generally included an outer side wall having an upper U-shaped rim about its edge and directed downward. The fitment is inserted into the container until the U-shaped rim securely fits over the upper edge of the container wall. Prior to inserting the fitment, past systems injected a bead of hot melt glue about the fitment along its outer periphery. In round containers, as the fitment was inserted, the upper portion of the inner wall of the container contacted the bead of hot melt glue and smeared the glue along the outer surface of the fitment and the inner surface of the container until the U-shaped rim engaged the top of the container.
The foregoing process worked satisfactorily for round containers and round fitments.
However, the above conventional process was unsatisfactory for non-round containers. Non-round containers generally include opposed long side walls which are quite flat, or include minimal curvature. These flat side walls are more difficult to maintain in a desired curvature or plane while inserting the fitment. Instead, the curvature of the side walls fluctuates slightly, differing from the curvature of the fitment. Hence, when the container fitment is inserted, the upper edge of the side wall portions contact the fitment below the glue bead. Such contact causes the upper edge of the container effectively to wipe the bead of hot melt glue off of the fitment as the fitment passes the container side wall. Consequently, the majority of the hot melt glue is forced out of the container and outside of the fitment, thereby producing an interconnection having less than 100% adhesion and thus less than 100% "fiber tear" between the container and fitment. This wiping operation further wastes glue and presents an overall dirty appearance upon the outside of the container.
An alternative system has been proposed in the past for round containers, in which a bead of hot melt glue is injected from a glue gun positioned remote from the container and located along one side thereof. The glue gun sprays a stream of glue downward into and across the open end of the container onto the opposite side wall as the container is rotated, thereby covering the interior perimeter of the container. However, this system has only proven effective with round containers since, as the non-round container was rotated while the glue gun remained stationary, the distance varied between the gun and container. Additionally, the relative velocity of the container side wall varied. Thus, systems utilizing a stationary gun with a non-round container experienced variations in the radial speed at which the glue was applied thereby changing the thickness of the bead. The system was unable to compensate and these variations in distance and relative velocity rendered it impossible to apply an even bead of glue to the container from a stationary gun.
A need remains in the industry for an apparatus capable of evenly applying hot melt glue to non-round containers. It is an object of the present invention to overcome the disadvantages heretofore experienced and meet this need.